The CT-imaging findings of primary renal PNET/Ewing's sarcoma in two patients were retrospectively assessed. A large renal mass with heterogenous contrast enhancement and necrotic and hemorrhagic areas were the predomi- nant characteristics. In adolescents or young adults presenting with a large renal mass, PNET/Ewing's sarcoma may be included in the differential diagnosis.

Primitive Neuroectodermal Tumor (PNET) or Ewing’s sarcoma of primary renal origin is a very rare entity with aggressive behavior. Affected patients are adolescents or young adults, with variable and aspecific clinical presentation. In most cases the presence of a renal tumoral mass is assessed with ultrasound or computed tomography, but the diagnosis of PNET/Ewing’s sarcoma is usually made only on histopathology after nephrectomy, based on immunohistochemical and cytogenetic tests. We report on the CT-imaging findings in two cases of renal PNET/Ewing’s sarcoma.